Peter W. Clark

Preparation and Nuclear Magnetic Resonance Study of Phosphorus Compounds Containing Alkenyl Functional Groups

The phosphines PPhn(CH2CH2CH=CH2)3−n, n = 2–0, PPhn(CH2CH2CH2CH=CH2)3−n, n = 1 or 2, and PPh2CH2CH = CH2 have been synthesized and studied by 1H and 31P magnetic resonance. The n.m.r. spectra of PPh2(OCH2CH=CH2), its oxide, O=PPh2(OCH2CH=CH2), and its Arbuzov rearrangement product, O=PPh2(CH2CH=CH2), have been investigated by 31P decoupling of the proton spectrum, selective proton decoupling of the 31P spectrum, and comparison with computer-simulated spectra to determine the spin–spin coupling constants. The n.m.r. spectra of the related oxides O=PPh2CH2CH2CH=CH2, O=P(CH2CH2CH=CH2)3, and O=P(OCH2CH=CH2)3 are also assigned. The data indicate that 3JPH > 2JPH for alkenylphosphines, 2JPH is larger for phosphine oxides than for phosphines, and 3JPH is little changed in comparing phosphorus(III) with phosphorus(V) compounds.

Olefin complexes of rhodium(I) containing the ligands but-3-enyldiphenylphosphine and diphenylpent-4-enylphosphine

Abstract But-3-enyldiphenylphosphine (mbp) and diphenylpent-4-enylphosphine (mpp) react with Rh2Cl2(C2H4)4 (molar ratio 2 1 to form the four coordinate dimeric complexes Rh2Cl2(mbp)2 and Rh2Cl2(mpp)2 respectively, while but-3-enyldiphenylphosphine reacts with Rh2Cl2(C2H4)4 (molar ratio 4 1 ) to form RhCl(mbp)2, a five coordinate complex in the solid state. The dimers further react with sodium tetraphenylborate to give the π-bonded tetraphenylborate complexes Rh[mbp][C6H5)4B] and Rh[i-mpp][(C6H5)4B] where i-mpp = (C6H5)2P(CH2CH2CHCHCH3). RhCl(CO)(mbp)2 reacts with sodium tetraphenylborate to form the five coordinate cationic complex [Rh(CO)(mbp)2][(C6H5)4B]. Both RhCl(CO)(mbp)2 and RhCl(mbp)2 react with hydrogen in methanol saturating the olefin to form RhCl[CO][(C6H5)2P(C4H9)]2 and Rh2Cl2[(C6H5)2P(C4H9)]2 respectively.

Tris-olefin complexes of rhodium(I) and iridium(I) containing the tetradentate ligands tris(but-3-enyl)phosphine and tris(pent-4-enyl)phosphine☆

The rhodium(I) and iridium(I) complexes, RhX(tbp), RhX(tpp), X = Cl, Br or I, and IrCl(tbp) and IrCl(tpp) where tbp = P(CH2CH2CH=CH2)3 and tpp = P(CH2CH2CH2CHCH2)3 have been prepared. These compounds, except for RhI(tbp), all exhibit the same “umbrella” type five coordinate structure in the solid state, in which all three olefins are bonded to the metal. At −60° in solution, RhI(tbp) adopts the same five coordinate stereochemistry. Due to restricted rotation, the methylene protons in RhCl(tbp) become inequivalent at low temperature. RhCl(tbp) forms 11 adducts with carbon monoxide and triphenylphosphine. Infrared, Raman and PMR studies conclude that the metalolefin bond is stronger for the iridium complexes compared to the corresponding rhodium complexes.

Five coordinate rhodium(I) olefin complexes containing the ligand bis(but-3-enyl)phenylphosphine

Abstract The complexes Rh2X2(bbp)2 (X = Cl, Br or I; and bbp = bis(but-3-enyl)phenylphosphine) have been prepared. These complexes have been characterized as five coordinate dimers in which the unsaturated phosphine acts as a tridentate ligand. Carbon monoxide reacts reversibly with the dimers forming the five coordinate monomeric compounds RhX(CO)(bbp). Mass spectral, infrared, Raman, and proton magnetic resonance data are consistent with the above formulations.

Crystal and molecular structure of chlorobis(3-butenyldiphenylphosphino)rhodium(I)

The structure of chlorobis(3-butenyldiphenylphosphino)rhodium(I) was determined by three-dimensional x-ray diffractometer techniques. The compound crystallizes in the space group P2/sub 1//c with cell constants of a = 10.697 (5) A, b = 9.832 (5) A, c , 36.44 (2) A, and ..beta.. = 96.42 (3)/sup 0/; Z= 4. The structure, solved by heavy-atom techniques, was refined by full-matrix least-squares methods using the 4218 reflections which had intensities 3 sigma above background to an unweighted R value of 5.1 percent. The coordination around the Rh(I) atom is best described as trigonal bipyramidal with one phosphorus and the midpoints of the two olefinic groups forming the equatorial plane which lies 0.13 A toward the Cl atom from Rh(I). In spite of the different geometric constraint imposed by the butenyl chains, both olefinic groups lie in the equatorial plane (within 8.5/sup 0/). This phenomenon and the placement of the best ..pi.. acceptor in the equatorial plane are interpreted in terms of a synergetic cooperation between the ..pi.. and sigma bonding in this plane.

The hydrogenation in methanol solution of the complexes. RhCl (CO) {PPh2[(CH2)n) CHCH2]}2 and PhCl(CO) [PPh2 (CH2CH2 CHCHCH3)]2.

The complexes RhCl (CO) {PPh[(CH)CHCH]} and RhCl (CO) {A figure is presented} add hydrogen in methanol solution saturating the olefin and forming RhCl (C0) {PPh [(CH)CH]}, n = 0-3. The reaction does not proceed in non-protic solvents. Carbon monoxide inhibits the reaction, whereas excess ligand (for n = 2) becomes catalytically saturated. The rate of the reaction depends largely on steric factors and follows the order RhCl (CO) [PPh (CHCHCHCH)] > RhCl (CO) [PPh(CHCHCH=CHCH)] ~ RhCl (CO) [PPh (CHCHCHCHCH)] > RhCl (CO) [PPh(CHCHCH)] > RhCl (CO) [PPh(CHCH)]. Deuteration experiments show that scrambling does occur and a mechanism for the hydrogenation is proposed. Isomerisation for n = 3 occurs at higher temperatures giving the cis-olefinphosphine complex RhCl (CO) {A figure is presented}.

Preparation and properties of group VI metal carbonyls containing the ligand bis(di-o-tolyl)phosphinomethane. Crystal and molecular structure of dicarbonylbis(di-o-tolyl)phosphinomethanechromium

Abstract Complexes of Group VI metal carbonyls with the ligand bis(di-o-tolyl)phosphinomethane have been prepared and characterised by NMR spectroscopy. The crystal structure of Cr(CO)2(BDToM) has been determined by conventional X-ray diffraction techniques. The orange tabular crystals are monoclinic, space group Cc, a 24.197(1), b 8.162(1), c 16.736(1) A, β 124.14(1)°, V 2735.8 A3, Z = 4. Refinement by full-matrix least-squares methods employed anisotropic thermal parameters for the heavier atoms and the coordinated o-tolyl group. One carbonyl ligand was positioned from a ‘difference’ map. The final residual, R, is 0.078 for 1673 observed reflections. The complex is monomeric. The BDToM ligand coordinates to chromium through one phenyl ring (three sites) and one phosphorus atom, with two carbonyl groups completing an octahedral ‘piano stool’-like arrangement. The coordinated arene ring is planar and is in a staggered arrangement relative to the other donors. The CrC(arene) bonds range from 2.166(10) to 2.260(9) A (average 2.210 A); the distance of Cr from the plane of the ring is 1.698 A. The o-methyl carbon and the non-coordinated phosphorus atom are significantly displaced from the ring plane.

The hydrogenation and isomerisation of unsaturated tertiary phosphine complexes of rhodium(I)

The hydrogenation (a two-step process) and isomerisation of RhCl(CO)[Ph2P(CH2)n·CHCH2]2, where n= 0, 1, 2, or 3, are controlled by the steric requirements of the ligand whose interactions are most favourable when n= 2.